I really wish I knew how to read Japanese for this one, so that I could figure out what was happen in detail. The summary describes it as a guy going into a pact with the ghost of a creepy girl as a result of accidentally snapping her in a selfie.
Then I'm going that that this leads to her banging him while he seem to be stuck in a sleep paralysis. Yeah, that's not making it any more creepy at all, I know.